gas uses ZSTD_compressStream2 which is only available with libzstd >=
1.4.0, leading to build errors when an older version is installed.
This patch updates the check libzstd presence to check its version is
>= 1.4.0. However, since gas seems to be the only component requiring
such a recent version this may imply that we disable ZSTD support for
all components although some would still benefit from an older
version.
I ran 'autoreconf -f' in all directories containing a configure.ac
file, using vanilla autoconf-2.69 and automake-1.15.1. I noticed
several errors from autoheader in readline, as well as warnings in
intl, but they are unrelated to this patch.
This should fix some of the buildbots.
OK for trunk?
Thanks,
Christophe
PR29397 PR29563: Add new configure option --with-zstd which defaults to
auto. If pkgconfig/libzstd.pc is found, define HAVE_ZSTD and support
zstd compressed debug sections for most tools.
* bfd: for addr2line, objdump --dwarf, gdb, etc
* gas: support --compress-debug-sections=zstd
* ld: support ELFCOMPRESS_ZSTD input and --compress-debug-sections=zstd
* objcopy: support ELFCOMPRESS_ZSTD input for
--decompress-debug-sections and --compress-debug-sections=zstd
* gdb: support ELFCOMPRESS_ZSTD input. The bfd change references zstd
symbols, so gdb has to link against -lzstd in this patch.
If zstd is not supported, ELFCOMPRESS_ZSTD input triggers an error. We
can avoid HAVE_ZSTD if binutils-gdb imports zstd/ like zlib/, but this
is too heavyweight, so don't do it for now.
```
% ld/ld-new a.o
ld/ld-new: a.o: section .debug_abbrev is compressed with zstd, but BFD is not built with zstd support
...
% ld/ld-new a.o --compress-debug-sections=zstd
ld/ld-new: --compress-debug-sections=zstd: ld is not built with zstd support
% binutils/objcopy --compress-debug-sections=zstd a.o b.o
binutils/objcopy: --compress-debug-sections=zstd: binutils is not built with zstd support
% binutils/objcopy b.o --decompress-debug-sections
binutils/objcopy: zstd.o: section .debug_abbrev is compressed with zstd, but BFD is not built with zstd support
...
```
